Real-time simulation refers to a
computer model
Computer simulation is the running of a mathematical model on a computer, the model being designed to represent the behaviour of, or the outcome of, a real-world or physical system. The reliability of some mathematical models can be determin ...
of a physical system that can execute at the same rate as actual "wall clock" time. In other words, the computer model runs at the same rate as the actual physical system. For example, if a tank takes 10 minutes to fill in the real world, it would take 10 minutes to fill in the simulation as well.
Real-time simulation occurs commonly in
computer gaming
A video game or computer game is an electronic game that involves interaction with a user interface or input device (such as a joystick, controller, keyboard, or motion sensing device) to generate visual feedback from a display device, mos ...
, but also is important in the industrial market for operator training and off-line controller tuning. Computer languages like
LabVIEW,
VisSim and
Simulink
Simulink is a MATLAB-based graphical programming environment for modeling, simulating and analyzing multidomain dynamical systems. Its primary interface is a graphical block diagramming tool and a customizable set of block libraries. It offe ...
allow quick creation of such real-time simulations and have connections to industrial displays and
programmable logic controller
A programmable logic controller (PLC) or programmable controller is an industrial computer that has been ruggedized and adapted for the control of manufacturing processes, such as assembly lines, machines, robotic devices, or any activity that ...
s via
OLE for
process control
Industrial process control (IPC) or simply process control is a system used in modern manufacturing which uses the principles of control theory and physical industrial control systems to monitor, control and optimize continuous Industrial processe ...
or digital and analog
I/O cards. Several real-time simulators are available on the market including xPC Target and
RT-LAB for mechatronic systems,
Simulink
Simulink is a MATLAB-based graphical programming environment for modeling, simulating and analyzing multidomain dynamical systems. Its primary interface is a graphical block diagramming tool and a customizable set of block libraries. It offe ...
for power electronic simulation, and RTDS for power grid simulation.
Definition
In a real-time simulation, the simulation is performed in
discrete time
In mathematical dynamics, discrete time and continuous time are two alternative frameworks within which variables that evolve over time are modeled.
Discrete time
Discrete time views values of variables as occurring at distinct, separate "poi ...
with a constant step (also known as fixed step) simulation as time moves forward in an equal duration of time. Other techniques having variable step are used for high frequency transients but are unsuitable for real time simulation. In a real time simulation, the time required to solve the internal
state equations and functions representing the system must be less than the fixed step. If calculation time exceeds the time of the fixed step, an over run is said to have occurred and the simulation now
lags behind the actual time. In simple words, real-time simulation must produce the internal variables and output within the same length of time as its physical counterpart would.
Configuring models to run in real-time enables one to use
hardware-in-the-loop simulation to test controllers. It's possible to make design changes earlier in the development process, reducing costs and shortening the
design cycle
A decision cycle or decision loop is a sequence of steps used by an entity on a repeated basis to Decision making, reach and implement decisions and to learn from the results. The "decision cycle" phrase has a history of use to broadly categorize v ...
.
In academic curricula
Real-time simulators are used extensively in many engineering fields. As a result, the inclusion of simulation applications in academic curricula can provide great value to the student. Statistical
power grid
''Power Grid'' is the English-language version of the second edition of the multiplayer German-style board game ''Funkenschlag'', designed by Friedemann Friese and first released in 2004. ''Power Grid'' was released by Rio Grande Games.
I ...
protection tests, aircraft design and simulation, motor drive controller design methods and
space robot integration are a few examples of real-time simulator technology applications.
OPAL-RT Technologies Technical Paper , Real-Time Simulation Technologies in Education: a Link to Modern Engineering Methods and Practices
/ref>
See also
* Human-in-the-loop
* Simulated Real Time, a literary method unrelated to the type of computer models described on this page.
References
{{reflist
External links
The What, Where and Why of Real-Time Simulation
HYPERSIM , The Power System Simulator of Tomorrow
From Offline Simulation to Real-Time Testing